Is This The Right Oil For My Bike?

Introduction

This report seeks to answer questions concerning use of the latest grade of motor oils in motorcycles. Motor oil standards have changes recently and some concerns have been raised, specifically by BMW, about use of this new oil grade in motorcycles. BMW, like many other engine manufacturers, sells a self-branded oil through its dealer network. To some, this raises the question of BMW's objectivity. Mobil 1, long a favorite of motorcyclists, has introduced a line of motorcycle-specific oils. They avoid the latest, questionable API rating, but at a price of double the already pricey automotive Mobil 1. What about old stand-bys like Castrol GTX and the bike-friendly Golden Spectro? They've been used for years. Are they still good? Have they actually changed at all? What's a biker to do?

In this study, the American Petroleum Institute (API) specifications are examined to determine what exactly has changed in the standards. Analysis was performed on a range of motor oils to quantify their additive packages. These packages were compared to the specifications and to each other to determine which were providing protection for engines, which had been depleted by the new specs, and which were selling snake oil.

If the optimum protection for your motorcycle is of interest to you, read on.

What's in this stuff?

To understand what all this fuss is about, one needs to know a little about motor oil. For purposes of this report, we will start with the base stock. This is the base oil formulation to which the oil company mixes in its chosen additive package. The additive packages are determined by the desired performance characteristics, weighed against cost of the additives, and as we shall see, limited by industry standards. For the purpose of this report, we will focus on the anti-wear and anti-corrosion additives.

Zinc and phosphorous are the prime anti-wear additives in today's motor oils. These additives provide protection from metal-to-metal contact on surfaces such as cam lobes and followers, as well as piston walls. They also protect at bearing surfaces when oil pressure is too low to build up a protective film, such as during engine cranking.

Sulfur is present in the gasoline we burn. During the combustion process, this sulfur can combine with oxygen to form sulfur dioxide, or sulfuric acid. This, along with other corrosive nasties, works its way past the piston rings and into the motor oil where it is pumped throughout the engine. To prevent these acids from destroying the internal machined surfaces, oil companies mix in anti-corrosion additives. These are typically magnesium, calcium (much like your favorite stomach antacid) and boron. These additives neutralize the acids being pushed into the oil and keep our engine innards nice and shiny.

Why are these API guys messing with my oil?

The American Petroleum Institute is an industry organization that, amongst other things, issues standards for petroleum products including motor oils. Oil companies agree to label their products with the appropriate API standard. This allows your motorcycle manufacturer to tell you that you need, for example, SH oil. Without such standards, they have to say you need an oil that passes ASTM D 2887 volatility test at 700 degrees with less than 18% loss. Imagine trying to compare all those test results while standing in the oil aisle at WalMart!

API has been grading oils for years. Chart A shows the progress of grades from the original SA to the latest SJ. Oils intended primarily for use in diesel engines are graded on a separate scale, ranging from CA up to the current CH.

To find what API grade your oil is, look for the "donut" on the bottle. The oil's viscosity is listed in the center of the donut. The API grade is listed on the upper half. The new fuel saving oils have "Energy Conserving" posted on the lower half of the donut.

Why is this new oil any different?

Despite the best effort of your piston rings and valve seals, some of your oil gets into the air flowing through your engine. In cars, and some bikes, this leads it straight through a catalytic converter. All those additives that are so great for protecting your engine are not so great for the catalyst. The Environmental Protection Agency has asked for a reduction of the anti-wear additive phosphorous due to its life-shortening effect on catalysts. When the new API oil grade, SJ, was released in 1996, phosphorus levels had been lowered from a maximum of 0.12% down to 0.10%.

But the reduction was only specified for oil viscosity of 0W-20 through 10W-30 (yes, there is a zero viscosity oil). The thicker oils were not required to meet this phosphorus level. That is not to say that they won't. Additives cost the oil companies money. If they can get by with less, they might be inclined to do so. Standardizing the additive packages across all viscosity would also simplify their lives.

Given this reduced level of phosphorous in some SJ oils, and the potential for it in others, BMW issued a service bulletin to address the issue. It said that SJ oils were not approved for use in BMW motorcycle engines. BMW recommended oils with API specifications of SF, SG, or SH. These are the previous grades which, in API's mind, had been superseded by the new SJ. BMW did not consider it a supersedure and threatened to void warrantees if the SJ oils were used.

Confusion reigned in the world of BMW riders. Were not their engines, especially in K bikes, very much like automotive engines: four cylinders, water cooled, dry clutch, separate transmission oil? BMW allowed SJ oils in their cars, why not the bikes? Other motorcycles manufacturers didn't object to SJ oil, what was the difference?

BMW finally attempted to clarify the issue by stating that the SJ rating was acceptable, if the oil was additionally rated at one of the previous SG and/or SH grades.

Problem solved, what's the big deal?

While it may have hoped that this answered the concerns of its customers, BMW actually raised more questions than they answered. Remember that the phosphorous levels are listed as a maximum allowable level. Any amount under the maximum, under 0.10% for SJ oil, is acceptable to API. So for an oil to be rated SH and SJ it still needs to be under the tighter SJ limit. Being additionally rated SH doesn't provide any more phosphorous! BMW's logic here is questionable.

In the course of this testing, the author spent a lot of time reading oil bottles. Of all of the oils in this test, and all the oils scanned in auto supply houses, none were rated SJ alone. All the SJ oils had additional grading of SH or SG. So if all oils have a multiple rating, what oil is BMW trying to protect us from?

Some questions obviously arise here. Your author set out first to find the right questions.

So what do we want to know?

When starting any kind of testing, its always a good idea to have specific questions in mind. This gives focus to the test and allows you to discard the superfluous data that distracts from your purpose. Questions like "what's the best oil" and "is synthetic better than petroleum oil" are great for starting bar fights, but are a bit too vague for the scope of this testing.

A survey was done of the internet BMW riding community. Their favorite oils were listed and whittled down to a manageable number. With these specific oils in mind, focused questions could be generated. Some that will hopefully be answered here include:

Was the phosphorous level actually dropped from SH to SJ oils?

Are BMW's own bike oils better than automotive oils?

What about the new Mobil 1 motorcycle oil? Is it better than Mobil 1 automotive?

Is there any difference between $1 per quart oil and $4 oil?

Read on, and you too can amaze your friends with trivial oil facts!

How was this testing done?

The testing reported here is the result of chemical analysis of new oils. The oil samples were submitted to National Tribology Services, Inc., of Peabody, Mass. NTS is a contracted lab that routinely does chemical analysis for industry. For oils, they use Rotrode Filter Spectroscopy for their investigations. Through a rather complex mechanism, a film of the subject oil is zapped with an electric arc, causing the oil to vaporize. The light emitted by the arc is read by the spectrograph. The wavelengths of the light specify the constituents of the oil.

This analysis method is commonly used for monitoring of engine conditions. Fleet operators interested in knowing if their engines' bearings are wearing, submit samples of used oil. The tests that detect traces of bearing bronze in used oil also work to identify the levels of phosphorous and zinc in new oils.

So the sample oils were tested for their levels of anti-wear and anti-corrosion additives. Analysis of the base oils and retention of additives or viscosity in used oils was beyond the scope of this testing. These issues are pertinent to a full understanding of motor oils, however, and may provide a good basis for some follow-on testing.

The Contestants

The oils included in this test are on Chart B. Its make-up may need a little explanation. The choice of BMW synthetic and petroleum oils is obvious. Castrol GTX is a favorite of many riders for many years. The selection of GTX 10W-30 and 20W-50 allows a comparison of an oil regulated by the API's SJ rating, and one exempted.

The Gulf Super Duty and the Valvoline Premium Blue are both primarily diesel oils. Note the CF and CG ratings. These were included to address the rumors that diesel oils offer better protection, specifically anti-corrosion protection, than do automotive oils.

Spectro Oils has made motorcycle specific oil for years. Its Golden Spectro has a strong following in the BMW community. The bottle of BMW petroleum oil says that it is formulated for BMW by Spectro Oils. Are they really the same oil?

The Mobil 1 oils present an interesting study by themselves. The motorcycle rated SG/SH oil (at $8 per quart!) could be contrasted to the automotive grade. Availability of an older automotive SH allowed for comparison to the newer SJ grade. And the Energy Conserving 10W-30 Mobil 1 would illustrate if Mobil varies their additive packages as they vary viscosity.

The Pennzoil GT and Valvoline Racing are popular oils available at discount stores at close to $1 per quart. Is the user sacrificing the life of his bike by saving a few bucks on these oils?

The Data

Chart C lists the levels of additives in the test oils. The numbers are in parts per million (PPM). Those of you that spent your time in math class doodling pictures of hot bikes will want to know that the 0.10% in the API specification translated to 1000 PPM, 0.12% equals 1200 PPM.

While all the answers lie in this chart, it is often easier to see trends by graphing specific data. Of prime interest is the levels of phosphorous in the samples. Graph D shows that the Golden Spectro Blend and the BMW petroleum SG oils contain the highest levels of phosphorous. The high viscosity Mobil 1 oils are closely grouped at 1050 to 1100 PPM. Note that the to Energy Conserving SJ oils, the Castrol GTX 10W-30 and the Mobil 1 10W-30 are both below 1000 PPM. This is in keeping with the API's 0.10% spec.

Graph E combines the zinc with the phosphorous levels. While the level of additive increases, note that the relationship between the oils stays the same. This is likely because the oil industry adds zinc and phosphorous as one chemical, ZDDP.

Graph F shows the level of acid neutralizing anti-corrosion additives in the oils. Here the pack is led by the synthetic oils, the Mobil 1 and BMW SH. This may well be related to extended change intervals used by some synthetic customers. The longer an oil is run in an engine, and some synthetics are going a long way, the more acid they need to neutralize.

So what about the Mobil 1 oils? Are they all the same? Graph G compares only the four Mobil oils for each of the five additives. Note that the first three oils, the higher viscosity ones, are all closely grouped. It is the opinion of the author that the additive packages in the old Mobil 1 SH, the current SJ, and the new motorcycle-specific SG/SH are all the same. The Energy Conserving Mobil 1 SJ has lower levels of all additives with the exception of magnesium.

How about the BMW oils? How do they compare, and are they the same as the Golden Spectro? Graph H highlights the two BMW oils, synthetic SH and petroleum SG, against Golden Spectro's synthetic blend. BMW's SG and the Golden Spectro have the most phosphorous and zinc anti-wear additives, respectively. BMW SH has far more calcium, while the other two lead in the other anti-corrosion additives. From this chart, it appears that the BMW SG oil is not a rebottled Golden Spectro.

And finally, do you get what you pay for? Are there differences between the cheaper oils and the costlier ones? The BMW SH, at $3.56 per quart, was chosen as having a good additive package. Graph J compares it to the "K Mart" oils that ranged from $1.29 to $1.89 (and are often available for less). There is an obvious difference in the approach to corrosion resistance, BMW favoring magnesium, most of the others choosing calcium. No obvious advantage here. But note the anti-wear additives. The BMW oil has far more zinc and phosphorous. It is also interesting to note that the cheaper oils contain near or below the 0.10% phosphorous mandated by API, despite their higher viscosity exempting them from the standard.

This chart also suggests that Castrol uses the same additive package in its 10W-30 Energy Conserving oil that it does in the 20W-50 more likely used by motorcyclists. This is an ominous sign for us all. Discussions with industry insiders reveal that the API's phosphorous specification for the Energy Conserving oils will drop again within the next few years. If oil producers continue to use a standardized additive package, these drops will further impact the oils we run in our bikes.

Summary - Did we answer anything?

Recalling the questions posed at the start of this report, lets see what has been learned.

Did the phosphorous levels drop with the new API specs? Not having examples of pre-spec oils to compare with all the current spec oils, this question can not be definitively answered. Where a comparison can be made, the Mobil 1 SH verses SJ, there appears to be no change. But those are 15W-50 oils that are exempted from the spec. In the cases of the thinner oils where the API spec applies, all complied with the low phosphorous standard.

Are BMW's oils better than the automotive oils? For anti-wear, the BMW SG oil is tough to beat. It has been shown to be better than the cheaper automotive oils, and ahead of Mobil 1 in wear fighters.

Mobil 1 motorcycle oil: is it worth buying? The viscosity of this bike oil has been changed from Mobil 1's standard 15W-50 to 20W-50. This just happens to be what Harley specs for their bikes. If you smell a marketing ploy here, you may want to trust your nose. The additive package appears the same amongst all the 50 weight Mobil 1 oils.

Is there a difference between $1 per quart and $4 oils? This appears to be a case where you do get what you pay for. The cheaper oils need to target their automotive customers, and can't afford additives that may only be needed by the fringe motorcycle market.

And what about the diesel oils and their rumored added protection? The rumors were not substantiated by this testing. Gulf Super Duty and Valvoline Premium Blue rated mid-field or lower on both anti wear and anti corrosion packages.

Future Activity

There is already work underway to establish an industry standard specifically for motorcycle oils. This was prompted not just by BMW's wear concerns, but by the Japanese manufacturers. Their wet clutch bikes are having slippage problems with some new oils. Expect to hear more of these new oils within a year. What is in them will make an interesting follow-on investigation.

As mentioned previously, there is a new API standard being prepared for automotive oils, likely to be called SK. It will reportedly lower phosphorous levels further, from SJ's 0.10% down to 0.08. A repeat of the type of testing done here may be justified at that time.

CHART A - API OIL CLASSIFICATIONS, Gasoline Engines

Category

Status

Service

SJ

Current

Introduced in the API Service Symbol in 1996. For all automotive engines presently in use.

SH

Obsolete

For model year 1996 and older engines. Valid when preceded by certain C categories.

SG

Obsolete

For model year 1993 and older engines.

SF

Obsolete

For 1988 and older engines.

SE

Obsolete

For 1979 and older engines.

SD

Obsolete

For 1971 and older engines.

SC

Obsolete

For 1967 and older engines.

SB

Obsolete

For older engines. Use only when specifically recommended by the manufacturer.

SA

Obsolete

For older engines; no performance requirement. Use only when specifically recommended by the manufacturer.